Three-point hitches are offered on most row crop and utility tractors. The front hitch is used to lift and carry various implements as well as ballast weights. When such a hitch is no in use, it is often desirable to be able to fold or otherwise retract the lift arms to reduce the overall length of the tractor. Currently, there are a variety of designs to allow the arms to be folded or stored.
In a typical known design, each the lift arm includes two parts or pieces. The first piece pivots on the tractor frame and is rotated up and down by the lifting hydraulic cylinders. The second piece is pinned to the first piece so that it can be rotated about a single generally horizontal pin to change the angle between the first and second pieces. In this manner, with the hitch in the raised position, the second piece of the lift arm can be folded rearward to a more vertical orientation to shorten the overall tractor length. Usually a second pin and different holes in one piece or the other allows the second piece of the arm to be locked in either the working or folded positions. Such an arrangement is currently used on some production John Deere tractors.
In some designs of this type, the pivot pin between the first and second parts of the lift arm is angled so that the outer end of the second part of the lift arm moves inboard or outboard as it is moved into the storage position. Typically, this is done to allow them to swing inboard, as is the case on the John Deere 5000 series tractor. This design can be advantageous when the tractor chassis is narrower than the spread of the hitch arms when in their working range. Alternately, an arm that swings outboard as it is moved into a storage position may be useful if the frame or other parts of the machine limit the distance an arm could be folded in a plane parallel to the tractor centerline.
In another hitch design used on Massey Ferguson 8600 series tractors, the two pieces of the lift arm both pivot about a common axis on the tractor frame. Again, the first piece is attached to the hydraulic lift cylinders to be rotated up and down. The second piece can be pinned to the first piece in two different orientations, one for and one for storage. The storage pin placement allows the normal hydraulic cylinder travel to rotate the second arm more than is desired for the working range of the hitch, which rotates it up and rearward, closer to the front of the tractor.
In some of the designs, the arms are moved into a folded storage position wherein the spacing between the implement ends of the arms is the same as the spacing in the working position. In such designs, it is possible to attach some implements to the hitch with the arms still in their folded position because they will still lower far enough to hook up. However, when the hitch is then raised, the now incorrect hitch geometry can cause the implement to lift too far, or may bind up the linkage, possibly damaging the tractor, hitch, or implement.